The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in the present disclosure and are not admitted to be prior art by inclusion in this section.
Signal communication within a digital system that includes different voltage domains is ensured by the use of voltage level shifters. These circuits are capable of converting a digital signal from one voltage domain to another without affecting its content. Contention-based circuits are used to implement voltage level shifters to ensure their operation within a wide range of voltage domains. However, large voltage differences between voltage domains can degrade the performance level of voltage level shifters or cause their failure. The propagation delay of a level shifter typically strongly depends on the voltage domain difference and is more pronounced when a signal is passed from a lower voltage domain to a higher one. In some situations, a level shifter may fail independently of the operating frequency of a system, resulting in failure of communication between the voltage domains. In some regions of operation before failure of the level shifter, the level shifter may be extremely sensitive to any variation (e.g., droops, noise, etc.) in the supply voltage. In this scenario, circuit paths including level shifters might suddenly limit the operating frequency or cause failures.